This shared facility affords members of the Center access to high quality cytometry and image analysis instrumentation and technical services. Instrumentation includes: (1) Coulter EPICS Elite flow cytometer/cell sorter; (2) Coulter EPICS Profile II flow cytometer; (3) Becton-Dickenson FACSCAN; (4) Meridian ACAS 570 image analysis system; and (5) Meridian Insight laser scanning confocal microscope. These instruments provide investigators with multiparameter analyses of cells, particles and tissue samples. Investigators can have samples analyzed by Facility staff, or can work with technical experts to analyze samples and resultant data. The Core is directed by Dr. Debra Laskin and is under the shared administrative control of EOHSI and CINJ. An advisory committee meets biannually, or as needed, with Drs. Laskin and Yurkow (Associate Director of the Facility Core) to review operations, usage priority policies and future plans. Priorities are set by Drs. D. Laskin and E. Yurkow and are based on the nature of the project and instrumentation required. Users can have access to instruments 24 hr per day, once Dr. Yurkow or the technicians train them. Charges for the use of the facility are based upon personnel time (including setup) and the cost of supplies. EHS Center support funds key personnel and defrays the costs of equipment maintenance. Charges to center members are 50% to 75% lower than to other academic users. Center members comprise 30-50% of all users; about 25 EHS Center members, from all four Research Cores, have used the Facility. Several examples were given of projects which highlight the importance of this Facility to the Center s interdisciplinary research. The Facility was recently expanded with new instruments and with overhauls of existing units. Future plans include: (1) upgrade of the Meridian ACAS system optics and computer; (2) replacement of the Coulter Profile II unit with an new instrument; and (3) expansion of current mini-courses and hands-on tutorials in methods of flow cytometry and image analysis.